Basic authentication using HMAC for federates joining a federation

[hokeun]

This PR is a submodule PR of the PR lf-lang/lingua-franca#1432 and is the first step towards resolving lf-lang/lingua-franca#1146. Both PRs should be merged to work.

Overall information is also in lf-lang/lingua-franca#1432. This PR details the HMAC authentication implementation.

This PR is about the RTI.c and federate.c authentication implementation.

The main idea of security is not to send the federation ID in plain text, by using it as an HMAC key.

3-Way Handshake

1. RTI_HELLO (RTI -> Federate)

The RTI sends a RTI_HELLO message to the federate when TCP connection is established. The message is in this order:

• One byte equal to MSG_TYPE_RTI_RESPONSE.
• Eight bytes for randomly created RTI's nonce.

2. FED_RESPONSE (Federate -> RTI)

The federate sends a response message to the RTI. It creates it's own nonce, and makes a HMAC tag using the federate ID as the key. The message is in the following order:

• One byte equal to MSG_TYPE_FED_RESPONSE.
• Eight bytes for federate's nonce.
• Two bytes for the federate ID.
• 32 bytes for HMAC tag based on SHA256.

The HMAC tag is composed of the following order:

• One byte equal to MSG_TYPE_FED_RESPONSE.
• Two bytes for the federate ID.
• Eight bytes for received RTI's nonce.

3. RTI_RESPONSE (RTI -> Federate)

The RTI sends a response message to the federate. It checks the received HMAC created by the federate, and also makes a HMAC tag. The message is in the following order:

• One byte equal to MSG_TYPE_RTI_RESPONSE.
• 32 bytes for HMAC tag based on SHA256.

The HMAC tag is composed of the following order:

• One byte equal to MSG_TYPE_RTI_RESPONSE.
• Eight bytes for received federate's nonce.

Federate Check

The federate finally checks the received HMAC created by the RTI.

Discussion

The 3-way handshake protocol does not change the existing federation id check process. receive_and_check_fed_id_message() still always happen after the 3-way handshake. So, the auth:true option only enables the 3-way handshake. Changing the protocol will be discussed at the future.

Also, the auth:true option will be changed from boolean to string in future.

[edwardalee]

I realize this is a draft, but it doesn't seem to perform any authentication. Guess this isn't ready for review?

[hokeun]

I realize this is a draft, but it doesn't seem to perform any authentication. Guess this isn't ready for review?

Thanks, @edwardalee for checking! You're right, this is not ready for review yet. I created this draft so that I can easily share my progress with others using Files Changed tap. I'll surely let you know when this is ready for review!

[Jakio815]

These changes are only for CI tests.

[lhstrh]

This looks good to me. Though I think that we might want to enable security by default and provide the option to disable it for whatever reason...